1. Field of the Invention
The invention relates to a universal tint paste having a high solids content and in particular to a universal tint paste for solvent-borne and high solids coatings that is substantially entirely solids.
2. Description of Related Art
Protective coatings serve to primarily preserve substrate integrity, but an important secondary function is to provide an aesthetically pleasing appearance to the substrates they protect. Pigments are a significant contributor to the overall visual appeal of a coating by adding gloss, opacity and color. In some cases, the aesthetics of the coating may be the deciding factor for a customer's purchase.
Coatings can be manufactured with the necessary pigments to provide the desired color, opacity, gloss and other desired characteristics. However, in order to increase the variety of colors and other properties that are available, manufacturers often will produce base coatings to which pigments are later added to produce a final coating having the desired color and other properties. The average consumer is more familiar with this in the context of purchasing paint from a retail store, where an automated system is used to add various pigments to a neutral base of the desired coating type to provide a final paint product having the desired color. Even when a coating product with the desired color and other properties is produced directly in a manufacturing facility, tint production batches are often manufactured separately and then added to the coating product prior to being packaged. In both cases, a separate composition is used to add the necessary pigments that provide the desired color, opacity, gloss and other desired characteristics to the particular base coating. The composition used to add the pigments to the base coating are considered tint pastes, but are also known as tint concentrates or colorants.
Tint pastes are made by dispersing pigments into a resinous vehicle. Traditional, commercially available tint pastes employ the use of surfactants, defoamers, wetting agents and solvents to assist in the dispersion of pigments into the resin. In some cases the pigments in solvent based tint pastes have a tendency to settle. This settling affects the distribution of the pigments in the tint paste. Given that the tint pastes are highly concentrated, even minor variations in the distribution of the pigments in the tint paste can have a noticeable effect on the color of the resulting coating. This is especially problematic in manufacturing facilities using tint production batches as the batches can be large and thus are more susceptible to variations in color etc. as a result of settling of the pigments.
In addition, solvents are major contributors of volatile organic compounds (VOCs). VOCs have been shown to cause harm to the environment and/or humans and animals. Due to a higher demand for eco-friendly products as well as conformance to increasingly strict environmental regulations, there is growing interest for low or non-volatile organic compound colorants.
Low-VOC tint pastes have been developed and are becoming commercially available in today's markets. However, they generally still rely on the use of solvents and simply exchange the prior more hazardous solvents for ones that are considered less hazardous and thus are currently exempt from the VOC restrictions and regulations. As the laws and regulations become more restrictive with respect to VOCs, these solvents may no longer enjoy their current exemption thereby eliminating these tint pastes as being low-VOC qualified products. Further, the VOC compliant tint pastes often have limited compatibility across different types of coating systems including for example, acrylics, polyurethanes, epoxies, alkyds, polyesters, room-temperature vulcanization silicones, cab lacquers, vinyl's, thermosets, thermoplastics and combinations thereof. These VOC compliant tint pastes also still require the use of additives and solvents in order to disperse the pigment, and, in some cases, improve compatibility with certain coating systems.
Existing solids colorants still contain additives and surfactants to aid in the dispersion and wetting of dry pigments. These colorants are carbon-based and therefore limited to specific coating systems.
Consequently, there is still a need for a tint paste that does not require the use of VOCs or other solvents and is compatible with a variety of coating systems.